DERIVATIVE INSTRUMENTS (Derivative Instruments in Financial Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Short-term derivative asset	$ 53,188	$ 126,201
Long-term derivative asset	4,298	563
Short-term derivative liability	(8,540)	(303)
Long-term derivative liability	(45,615)	(53,135)
Total net asset derivative position	3,331	73,326
Commodity Contracts
Derivatives, Fair Value [Line Items]
Short-term derivative asset	53,188	125,383
Long-term derivative asset	4,298	0
Short-term derivative liability	(8,540)	(303)
Long-term derivative liability	(45,615)	(53,135)
Total net asset derivative position	3,331	71,945
Contingent consideration arrangement
Derivatives, Fair Value [Line Items]
Short-term derivative asset		818
Long-term derivative asset	0	563
Total contingent consideration derivative position	$ 0	$ 1,381

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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